QSortFilterProxyModel: Keep invalid index updated on source model sort

If we have a filter applied that removes all entries, the source
model is sorted, and then we remove the filter, QSortFilterProxyModel
never emits rowsInserted. This is because it doesn't have the correct
source mapping and doesn't update when the filter is removed.

Change-Id: I447b2d150e509b128d27f4dabc4e081ca4ef037f
Task-number: QTBUG-46282
Reviewed-by: Olivier Goffart (Woboq GmbH) <ogoffart@woboq.com>

2 files changed, 48 insertions, 0 deletions

diff --git a/src/corelib/itemmodels/qsortfilterproxymodel.cpp b/src/corelib/itemmodels/qsortfilterproxymodel.cpp
index 15798d5293..5ae4fc0417 100644
--- a/src/corelib/itemmodels/qsortfilterproxymodel.cpp
+++ b/src/corelib/itemmodels/qsortfilterproxymodel.cpp
@@ -272,6 +272,7 @@ public:
     QModelIndexPairList store_persistent_indexes();
     void update_persistent_indexes(const QModelIndexPairList &source_indexes);
 
+    void filter_about_to_be_changed(const QModelIndex &source_parent = QModelIndex());
     void filter_changed(const QModelIndex &source_parent = QModelIndex());
     QSet<int> handle_filter_changed(
         QVector<int> &source_to_proxy, QVector<int> &proxy_to_source,
@@ -1045,6 +1046,19 @@ void QSortFilterProxyModelPrivate::update_persistent_indexes(
     q->changePersistentIndexList(from, to);
 }
 
+/*!
+  \internal
+
+  Updates the source_index mapping in case it's invalid and we
+  need it because we have a valid filter
+*/
+void QSortFilterProxyModelPrivate::filter_about_to_be_changed(const QModelIndex &source_parent)
+{
+  if (!filter_regexp.pattern().isEmpty() &&
+        source_index_mapping.constFind(source_parent) == source_index_mapping.constEnd())
+    create_mapping(source_parent);
+}
+
 
 /*!
   \internal
@@ -2304,6 +2318,7 @@ QRegExp QSortFilterProxyModel::filterRegExp() const
 void QSortFilterProxyModel::setFilterRegExp(const QRegExp &regExp)
 {
     Q_D(QSortFilterProxyModel);
+    d->filter_about_to_be_changed();
     d->filter_regexp = regExp;
     d->filter_changed();
 }
@@ -2325,6 +2340,7 @@ int QSortFilterProxyModel::filterKeyColumn() const
 void QSortFilterProxyModel::setFilterKeyColumn(int column)
 {
     Q_D(QSortFilterProxyModel);
+    d->filter_about_to_be_changed();
     d->filter_column = column;
     d->filter_changed();
 }
@@ -2350,6 +2366,7 @@ void QSortFilterProxyModel::setFilterCaseSensitivity(Qt::CaseSensitivity cs)
     Q_D(QSortFilterProxyModel);
     if (cs == d->filter_regexp.caseSensitivity())
         return;
+    d->filter_about_to_be_changed();
     d->filter_regexp.setCaseSensitivity(cs);
     d->filter_changed();
 }
@@ -2415,6 +2432,7 @@ void QSortFilterProxyModel::setSortLocaleAware(bool on)
 void QSortFilterProxyModel::setFilterRegExp(const QString &pattern)
 {
     Q_D(QSortFilterProxyModel);
+    d->filter_about_to_be_changed();
     d->filter_regexp.setPatternSyntax(QRegExp::RegExp);
     d->filter_regexp.setPattern(pattern);
     d->filter_changed();
@@ -2429,6 +2447,7 @@ void QSortFilterProxyModel::setFilterRegExp(const QString &pattern)
 void QSortFilterProxyModel::setFilterWildcard(const QString &pattern)
 {
     Q_D(QSortFilterProxyModel);
+    d->filter_about_to_be_changed();
     d->filter_regexp.setPatternSyntax(QRegExp::Wildcard);
     d->filter_regexp.setPattern(pattern);
     d->filter_changed();
@@ -2443,6 +2462,7 @@ void QSortFilterProxyModel::setFilterWildcard(const QString &pattern)
 void QSortFilterProxyModel::setFilterFixedString(const QString &pattern)
 {
     Q_D(QSortFilterProxyModel);
+    d->filter_about_to_be_changed();
     d->filter_regexp.setPatternSyntax(QRegExp::FixedString);
     d->filter_regexp.setPattern(pattern);
     d->filter_changed();
@@ -2522,6 +2542,7 @@ void QSortFilterProxyModel::setFilterRole(int role)
     Q_D(QSortFilterProxyModel);
     if (d->filter_role == role)
         return;
+    d->filter_about_to_be_changed();
     d->filter_role = role;
     d->filter_changed();
 }
diff --git a/tests/auto/corelib/itemmodels/qsortfilterproxymodel/tst_qsortfilterproxymodel.cpp b/tests/auto/corelib/itemmodels/qsortfilterproxymodel/tst_qsortfilterproxymodel.cpp
index 01c10886c5..bd9e858091 100644
--- a/tests/auto/corelib/itemmodels/qsortfilterproxymodel/tst_qsortfilterproxymodel.cpp
+++ b/tests/auto/corelib/itemmodels/qsortfilterproxymodel/tst_qsortfilterproxymodel.cpp
@@ -87,6 +87,7 @@ private slots:
     void filter_qtbug30662();
 
     void changeSourceLayout();
+    void changeSourceLayoutFilteredOut();
     void removeSourceRows_data();
     void removeSourceRows();
     void insertSourceRows_data();
@@ -1533,6 +1534,32 @@ void tst_QSortFilterProxyModel::changeSourceLayout()
     }
 }
 
+void tst_QSortFilterProxyModel::changeSourceLayoutFilteredOut()
+{
+    QStandardItemModel model(2, 1);
+    model.setData(model.index(0, 0), QString("b"));
+    model.setData(model.index(1, 0), QString("a"));
+    QSortFilterProxyModel proxy;
+    proxy.setSourceModel(&model);
+
+    int beforeSortFilter = proxy.rowCount();
+
+    QSignalSpy removeSpy(&proxy, &QSortFilterProxyModel::rowsRemoved);
+    // Filter everything out
+    proxy.setFilterRegExp(QRegExp("c"));
+    QCOMPARE(removeSpy.count(), 1);
+    QCOMPARE(0, proxy.rowCount());
+
+    // change layout of source model
+    model.sort(0, Qt::AscendingOrder);
+
+    QSignalSpy insertSpy(&proxy, &QSortFilterProxyModel::rowsInserted);
+    // Remove filter; we expect an insert
+    proxy.setFilterRegExp(QRegExp(""));
+    QCOMPARE(insertSpy.count(), 1);
+    QCOMPARE(beforeSortFilter, proxy.rowCount());
+}
+
 void tst_QSortFilterProxyModel::removeSourceRows_data()
 {
     QTest::addColumn<QStringList>("sourceItems");